The proposed study is an investigation of the relationship between depression, cerebral function, cognitive function and the social environment in the elderly (65 years old and over). We propose to study a number of variables on four populations of subjects (normal elderly, elderly with depression, with dementia, and with depression and dementia) in an attempt to develop descriptors and discriminators for these separate groups which can be used by all workers in the mental health area in their daily work. The variables which are to be studied longitudinally at 6-month intervals include: 1. Past medical history and physical illnesses, 2. Past life events, 3. Current emotional status with measures including depression, anxiety, emotional support, 4. Current social activities, 5. Cognitive function tests to document the actual quality and quantity of intellectual impairment, and 6. Cerebral function tests to include the electroencephalogram and cerebral blood flow, using the non-invasive technique, as a method of assessing cerebral impairment.